1. Field of the Invention
The present invention relates to a touchpad, and particularly to an optical touchpad with power-saving functions.
2. Description of the Prior Art
Portable electronic devices, such as mobile phones, are already widely used by the public. Under intense market competition, all manufacturers are forced to come up with new features for the portable electronic device. However, portable electronic devices are ultimately powered by their battery, which means that standby time is limited by battery capacity. Thus, manufacturers are keenly interested in technologies that can lower power consumption in portable electronic devices with limited battery power.
The backlight module accounts for the highest power consumption in traditional portable electronic devices. Thus, effective reduction of power consumption in the backlight module can greatly extend standby time of the portable electronic device. For example, when the user has not used his/her mobile phone for a period of time, the backlight module automatically turns off. Or, when ambient light near the portable electronic device is intense, backlight module intensity is increased.
However, the portable electronic device must include extra circuitry to be able to detect environmental light intensity, which incurs even more power consumption. Thus, even if the extra circuitry is added to the portable electronic device to detect environmental light, the amount of power savings provided is limited, and cannot truly extend the standby time effectively, which is inconvenient for the user.